(defun appd (l x)
  ;(if (null (rest l))
  (cond 
	((null l) (cons x nil))
	((null (rest l)) (cons (first l) (cons x nil)))
	(T (cons (first l) (appd (rest l) x)))))
(print (appd '(1 2) 3))
(print (appd nil 3))
